The present invention relates to wireless active eyewear for use in viewing field sequential stereoscopic images. Stereoscopic eyewear of this type has been discussed in the following U.S. patents by Lipton et al.: U.S. Pat. No. 4,884,876 (1989) entitled "ACHROMATIC LIQUID CRYSTAL SHUTTER FOR STEREOSCOPIC AND OTHER APPLICATIONS;" U.S. Pat. No. 4,967,268 (1990) entitled "LIQUID CRYSTAL SHUTTER SYSTEM FOR STEREOSCOPIC AND OTHER APPLICATIONS;" U.S. Pat. No. 5,117,302 (1992) entitled "HIGH DYNAMIC RANGE ELECTRO-OPTICAL SHUTTER FOR STEREOSCOPIC AND OTHER APPLICATION;" and U.S. Pat. No. 5,181,133 (1993) entitled "DRIVE METHOD FOR TWISTED NEMATIC LIQUID CRYSTAL SHUTTERS FOR STEREOSCOPIC AND OTHER APPLICATIONS."
Products following the art taught in these above mentioned patents have been manufactured and offered for sale by StereoGraphics Corporation under the CrystalEyes.RTM. trademark. Similar products have been offered in the marketplace by IMAX, Tektronix, and others.
Such products have certain basic features in common, in particular, liquid crystal (LC) shutters are driven electrically by on-board circuits and batteries, and synchronization information with regard to the field rate of the video source is received by an infrared (IR) sensor. This synchronization information is used to electrically drive the LC shutters out of phase with each other and in sequence with the video fields. (The term video is used in the generic sense of electronic images which are raster scanned.)
StereoGraphics' experience with manufacturing and marketing the CrystalEyes.RTM. product has resulted in a continuous examination of the product design. We believe that improvement is possible in terms of instrumentation and cost of manufacture of such products, and this disclosure will describe several concerns and how they have been addressed.
One concern was the need for turning the eyewear on and off. Presently, an on-off button is used, but people are not used to operating a button when wearing eyewear. It would be desirable if the CrystalEyes product was more like ordinary eyewear in this regard in order to heighten user acceptance and enjoyment of the product, i.e., if it did not need an on/off button. Moreover, if one forgets to turn off the eyewear, battery drain and reduction of battery life result without any user benefit.
The present CrystalEyes product has a circuit that turns off the eyewear after an interval of several minutes, but only if is not left facing the monitor/emitter. The continuous detection of an emitted IR sync signal enables the eyewear such that it will not turn off.
Another area of concern is the fact that the LC shutters are made of thin glass and may be broken on occasion, usually because the eyewear has fallen onto a hard surface. Tektronix and IMAX have both addressed this problem by surrounding the LC shutters with a shock absorbing rubber gasket.
Still another area of concern is the electrical connection between the LC shutters and the circuit board. Both elastomeric connectors and soldered wires have been used. Both have their advantages and disadvantages. A method has been sought to obtain a good electrical contact and to reduce the cost of manufacture of this necessary assembly step.
Yet another area of concern is the nosepiece of the eyewear. For greatest comfort it was felt that a rubber or soft nosepiece should be used. However, the addition of such a nosepiece adds a manufacturing step, and the part itself has some cost.